Hydrocarbon gasification



1961 .1. J. VAN ROSSUM ETAL 2,971,829

HYDROCARBON GASIFICATION 2 Sheets-Sheet 1 Filed Dec. 23, 1958 FIG.

INVENTORS:

JACOBUS J. VAN ROSSUM MARINUS J. HOFSTEDE THEIR ATTORNEY Feb. 14, 1961Filed Dec. 23, 1958 2 Sheets-Sheet 2 FIG. 4

INVENTORS:

JACOBUS J. VAN ROSSUM MARINUS J. HOFSTEDE BYJ THEIR ATTORNEY UnitedStates Patent 1 2,971,829 HYDROCARBON GASIFICATION Jacobus J. Van Rossumand Marinus J. Hofstede, Delft, Netherlands, assignors to Shell OilCompany, New York, N.Y., a corporation of Delaware Filed Dec. 23, 1958,Ser. No. 782,471 3 Claims. (Cl. 48-196) This invention relates toimprovements in a process for the preparation of gas mixtures containinghydrogen and carbon monoxide by partial combustion of liquid or gaseoushydrocarbon materials with an oxygen-containing gas. The expressionoxygen-containing gas is used herein to include air, oxygen-enriched airand substantially pure oxygen.

In a known process for the manufacture of synthesis gas through patrialcombustion of a first and second fluid with usually the addition ofsteam, one of the fluids (which may be either a carbonaceous fuel or anoxygencontaining gas) is fed tangentially into a first zone (sometimesdescribed as a whirl chamber) which has a boundary of a surface ofrevolution with a velocity suflicient to form an annular, rotatingcolumn which advances forwardly toward an open throat in one end of thewhirl zone. There is a gradual reduction in the cross section of thewhirl zone and accordingly a like reduction in the cross section of theannular rotating column to the dimen-' sion of the throat. The otherfluid (which may be either a carbonaceous fuel or an oxygen-containinggas but differing from the first fluid) is injected outwardly in ahollow cone from a conduit disposed axially within the whirl chamberinto the encompassing rotating, annular column of the first fluid. Thisinjection occurs adjacent the restricted throat. There occurs a rapidexpansion of the outwardly moving, rotating column from the restrictedthroat into a sharply enlarged combustion or reaction zone which alsohas a boundary wall of substantially a surface of revolution. Normallysteam is supplied to the combustion chamber through the tbroat-intherotating annular column, having been admitted with the first fluid inthe formation of the rotating column. If the hydrocarbon used is liquidthe annular rotating column will generally be the oxygen-containing gas,with the liquid hydrocarbon being injected outwardly into that column.However, if the hydrocarbon is gaseous, it may be employed to form theouter, rotating annular column and the oxygen-containing gas (hereoxygen or a very rich oxygen stream) will be centrally introduced.

The process of the foregoing description is designed to provide anintimate mixing of fuel and combustion air supplied to the combustionzone. The formation of double gas vortices as described in U.S. PatentNo. 2,806,517, Te Nuyl, leads to the desired combustion without therequirement of excess air. It has developed that for the optimumoperation of the process, there should be rela- I 2,971,829 PatentedFeb. 14, 1961 i Fig. 1;

tively uniform distribution of the gas'supplied to the flected in thecombustion zone, leading to irregularities of distribution whichinterfere with the reaction.

It is an object of this invention to provide an improved process whereinthere is a more uniform distribution of the gases supplied to thereaction zone. This and other objects will become more apparent with areading of the following disclosure, taken in conjunction with thedrawings wherein:

Fig. 1 is a longitudinal cross-section of an apparatus suitable for theperformance of theprocessof the in- V vention;

Fig. 3 is a graph of the circumferential pressure profile of anapparatus of the general design of that of Figs. 1 and 2, taken at thethroat of the apparatus, showing the variations of pressure around thefull 360 circumference of the throat; and

Fig. 4 is a circumferential pressure profile of an apparatus having adesign generally like that of Patent No. 2,806,517, again with theprofile being taken at the throat of the apparatus, showing thevariations of pressure around the full 360 circumference of the throat.

It has now been discovered that the annular rotating column of gassupplied to the combustion zone of the aforementioned described processmay be provided with a more uniform pressure distribution when the firstfluid is introduced into the first zone (Whirl zone) through the severalopenings at an angle defined by a tangential line to an imaginarycylinder having a diameter not greater than two-thirds of the diameterof the first zone and not less than the diameter of the axially disposedconduit (obstruction) of that zone, the latter referred to conduit beingthe conduit through which the second fluid is furnished. Furthermore,each of the several openings into the first zone is a slot of arestricted area designed to provide a pressure drop thereover in excessof the maximum pressure diiferential existing between any two points inthe encircling plenum. In the preferred embodiment the first fluid isadmitted to the plenum at an angle designed to impart to the enteringfirst fluid the same directional rotation within the plenum as exhibitedby the first fluid flowing through the first zone (whirl zone). Thepressure drop across the individual slots is preferably in excess of twoand one-half times the largest pressure variant in the plenum.

With reference to the drawings, the apparatus illustrated in Figs. 1 and2 includes a combustion chamber 11 enclosed in a refractory wall 12which is connected axially through a throat 13 in one end thereof to anaxially aligned whirl chamber 15. Both chambers have circularcross-sections and in the instance of the whirl chamber there is agradual tapering (a cone formation) to the dimension of the restrictedthroat connecting the two chambers. This gradual reduction in thecross-section of the whirl chamber or zone results in a correspondingreduction in the cross-section of the annular rotating column of gasformed therein. It will be seen that the first fluid, normally oxygen oroxygen enriched air, is admitted through a line 14 and a tangentialopening 16 to the interior of a plenum 17 which encircles the whirlchamber, being separated by a cylindrical bushing 18. Steam may be andis customarily introduced with the air to the plenum and from therethrough the whirl chamber to the combustion zone.

The wall of the cylindrical bushing 13 separating the plenum and whirlchamber is relatively thick and is provided with eight elongated slotsof limited cross-section, especially designed to obtain a large drop inpressure. In the instance where the gasification process is carried onat a relatively high pressure, say in excess of 10 atm., it isadvantageous to take one-half of an atmosphere pressure drop across theslots. Generally speaking, it is preferred that the pressure drop acrossthe individual slots be in excess of two and one-half times the largestpressure variant existing in the surrounding plenum. It is alsodesirable to round oflt'the walls of the several slots on the inlet(upstream) side, thus permitting the gas stream to pass through the,slots with less disturbance, and thereby promoting a more uniforminflow. The gas supplied to the plenum rotates in the same direction asthe stream passing through the whirl chamber. 1

far end a nozzle'22 which terminates adjacent the throat The hydrocarbonfluid is injected outwardly in a hollow cone into the rotating annularcolumn of air.

, The several elongated slots of the whirl chamber wall open at an angledefined by a tangential line to the cylindrical feed tube support. Bydirecting the slots in this fashion a larger degree of homogenizing maybe obtainedthan in the instance of the arrangement of the slots in atangential direction to the inner diameter of the whirl chamber. Theangle of introduction of the air through the several slots of the whirlchamber wall is preferably defined by a tangential line to an imaginarycylinder having a diameter not greater than two-thirds the diameter ofthe whirl chamber nor less than the diameter of the axially disposedconduit lying within the whirl zone. In this connection the term axiallydisposed conduit (obstruction) includes the cylindrical support 23.

The lower section of the wall of the whirl chamber, that is the portionadjoining the combustion chamber, is provided with an internal annularchannel 25 which is supplied with cooling water through an internalinlet conduit -27. The outlet line for the'water passing through theannular channel is a second internal conduit 28. The wall of thecombustion zone is likewise supplied with a cooling jacket 36 whichcompletely encompasses'thc wall of that zone. Here the cooling water isintroduced through a line 32 to the down-stream side of the combustionzone. The water circulates throughout the jack et 30, leaving via anexit line 33.

It has been found that the process of the invention may be successfullypracticed with an apparatus of the following dimensions:

Cross-sectional area of supply line 1 4 sq. mm 7050 Largest insidediarnetcr of the plenum 17 mm 2 80 Outside diameter of thewhirl chamberwall mm 190' Inside diameter of the whirl chamber wall -mm..- 150 Numberof slots in the whirl chamber wall 8 Width of the slots mm.. 3 Effectivelength of the slots mm- 15 Height of the slots mtn 183 -Diameter of theimaginary cylinder in relation to-which the slots are arrangedtangentially mm 78 Effective length of the slots referred to in the data20 table above is the actual lengthof a slot of like effectiveness notutilizing the rounding ed on the inlet (upstream) side of the slots. Theheight of the slots is the dimension of the slot parallel to the axis ofthe whirl chamber. The width of the slot is the smallest dimension ofthe slots, best illustrated in Fig. 2'. It was found that witlrthe useof the apparatus having the above-mentioned dimensions the pressure dropover the several slots was approximately two and one-half times as largeas the largest prmsure variant in the plenum.

The advantages to be had in the use of the processof the invention arestrikingly demonstrated in the graphs of Figs. 3 and 4. The graphsrespectively depict the circumferential pressure profiles obtained. inthe operation of an apparatus of the design of Figs. 1 and.2 and ofamore conventional apparatus of the general design of Patent No.2,806,517. Both apparatus had a rated capacity of 3.00 kilograms perhour of hydrocarbon. Structurally, the two apparatus were essentiallyalike except for the design of the slots and the angle of introductionof the air to the whirl chamber. Theair inlet slots of the whirl chamberWall of the apparatus of Fig. 4 are designed for a minimum pressuredrop. And in this particular, instance the walls ofthe several ports(12in number) have the, cross-section of .an air foil, rounded and ofgreater thickness at the inlet side and tapering to the outlet side.Such a design is recognized to give a minimum pressure drop. In contrastthe several ports of the apparatus of Figs. 1 and 2, the operation ofwhich is reported in Fig. 3 were purposely designed to provide asignificant pressure drop of approximately one-half an atmosphere withtheapparatus operating at a pressure somewhat in excess of atmospheresIn Figs. 3

. and .4,-P .;stands for reference pressure .and R is a pressure takenaround the throat of the respective ap paratus. The reference pressureintheinstance of Fig. 3 is approximately 80 mm. mercury gaugeand in theother graph approximately 90 mm. mercury gauge. The slots of theapparatus of Fig. 3 had a width of 3 mm. and a height of approximately100 mm." The air foil ports of the other apparatus presented a minimumwidth of approximately. 3.7 mm. and a height of approximately- 85 Thelatter apparatusincorporated 12 air foils. Theg'raph of each of the twofigures presents a circumferential pressure profile taken at the throatof the respective apparatus, that is at the restricted passagewayconnecting the whirl chamber and the combustion zone. The data of theordinates of both graphs is the percentage variation. obtained ,in theoperation of the respectiveprocesses. It will be seen that there is asignificant improvement in the pressure distributions to be had in theuse .of the improved process, there the maximumpressure variation is2.3% whereas in the other case the pressure variation was approximately10%.

We claim as our invention:

1. In a method of preparing gas mixtures contain ing predominentlyhydrogen and carbon monoxide by partial combustion of a first and secondfluid, one of the fluids. being a carbonaceous fuel and the otheranoxygene containing gas,;wherein the first fluid is introduced from anouter encircling plenum at an angle through a plurality of openings intoa first zone having aboundry of a surface of. revolution with avelocitysufiicient to form an annular rotating column of said firstfluid advancing forwardly toward an open throat in one end of said zoneand wherein there is a gradual reduction in the cross section of saidzone and accordingly of the annular rotating column to the dimension ofsaid throat and wherein there is an injection of thesecond fluidoutwardly from aconduit disposed axially. within said first zone intothe rotating annular column of the first fluid and wherein there occursa rapid expansion of the outwardly moving, rotating column from therestricted throat into a sharply enlarged combustion zonehaving aboundary wall of substantially a surface of revolution, the improvementcomprising introducing the first fluid into the first zone through theseveral openings at an angle defined bya tangential line-to an imaginarycylinder having adiameter not greater than two-thirds of the diameter ofthe first zone andv not less than the diameter of the axiallydisposedconduit of said zone, and providing a pressure drop over each.of saidiplurality of openings between the plenumfandthe. first zone inexcess of the maximum pressurev differential existing between any twopoints in the plenum.

2. ,A process in accordance with claim l'wherein the first fluid isadmitted to the plenum at an angle adequate to impart to the enteringfirst fluid the same direction of rotation within the plenum asexhibited by that portion References Cited in the file of this patentUNITED STATES PATENTS ,517 Te Nuyl Sept. 17, 1957 FOREIGN PATENTS720,120 7 Great Britain Jul 31. 1951

1. IN A METHOD OF PREPARING GAS MIXTURES CONTAINING PREDOMINENTLYHYDROGEN AND CARBON MONOXIDE BY PARTIAL COMBUSTION OF A FIRST AND SECONDFLUID, ONE OF THE FLUIDS BEING A CARBONACEOUS FUEL AND THE OTHER ANOXYGENCONTAINING GAS, WHEREIN THE FIRST FLUID IS INTRODUCED FROM ANOUTER ENCIRCLING PLENUM AT AN ANGLE THROUGH A PLURALITY OF OPENINGS INTOA FIRST ZONE HAVING A BOUNDRY OF A SURFACE OF REVOLUTION WITH A VELOCITYSUFFICIENT TO FORM AN ANNULAR ROTATING COLUMN OF SAID FIRST FLUIDADVANCING FORWARDLY TOWARD AN OPEN THROAT IN ONE END OF SAID ZONE ANDWHEREIN THERE IS A GRADUAL REDUCTION IN THE CROSS SECTION OF SAID ZONEAND ACCORDINGLY OF THE ANNULAR ROTATING COLUMN TO THE DIMENSION OF SAIDTHROAT AND WHEREIN THERE IS AN INJECTION OF THE SECOND FLUID OUTWARDLYFROM A CONDUIT DISPOSED AXIALLY WITHIN SAID FIRST ZONE INTO THE ROTATINGANNULAR COLUMN OF THE FIRST FLUID AND WHEREIN THERE OCCURS A RAPIDEXPANSION OF THE OUTWARDLY MOVING, ROTATING COLUMN FROM THE RESTRICTEDTHROAT INTO A SHARPLY ENLARGED COMBUSTION ZONE HAVING A BOUNDARY WALL OFSUBSTANTIALLY A SURFACE OF REVOLUTION, THE IMPROVEMENT COMPRISINGINTRODUCING THE FIRST FLUID INTO THE FIRST ZONE THROUGH THE SEVERALOPENINGS AT AN ANGLE DEFINED BY A TANGENTIAL LINE TO AN IMAGINARYCYLINDER HAVING A DIAMETER NOT GREATER THAN TWO-THIRDS OF THE DIAMETEROF THE FIRST ZONE AND NOT LESS THAN THE DIAMETER OF THE AXIALLY DISPOSEDCONDUIT OF SAID ZONE, AND PROVIDING A PRESSURE DROP OVER EACH OF SAIDPLURALITY OF OPENINGS BETWEEN THE PLENUM AND THE FIRST ZONE IN EXCESS OFTHE MAXIMUM PRESSURE DIFFERENTIAL EXISTING BETWEEN ANY TWO POINTS IN THEPLENUM.